WJEC Biology A-level Topic 2.3: Adaptations for Transport

These flashcards cover key concepts from the WJEC Biology A-level notes on adaptations for transport, focusing on circulatory systems, the heart, haemoglobin, xylem and phloem, transpiration, and water movement in plants.

What are the two types of circulatory systems mentioned in the notes?

Open circulatory system and closed circulatory system.

What is the main function of arteries?

To carry blood away from the heart to the rest of the body.

How many chambers does a double circulatory system heart have?

Four chambers.

What is the primary role of capillaries?

Site of metabolic exchange, one cell thick for fast exchange of substances.

What characterizes venules?

Larger than capillaries but smaller than veins.

What is hydrostatic pressure in relation to circulatory systems?

Pressure created when blood is pumped along arteries and capillaries, forcing fluid out.

What does the lymphatic system do with excess tissue fluid?

Carries it back to the bloodstream.

How does the sinoatrial node function in the heart?

Initiates a wave of electrical stimulation causing the atria to contract.

What are the three stages of the cardiac cycle?

Atrial systole, ventricular systole, cardiac diastole.

What is the function of haemoglobin?

To carry oxygen in the blood.

What is the Bohr effect?

The decrease in haemoglobin's affinity for oxygen in the presence of carbon dioxide.

What are the main components of the vascular bundle?

Xylem and phloem.

What do xylem vessels transport?

Water and minerals.

What is transpiration?

The process where plants absorb water and release vapor through stomata.

What adaptations do xerophytes have to minimize water loss?

Smaller leaves, thick cuticle, and reduced stomatal opening.

How do water and minerals move through root hair cells?

Water moves by osmosis down a potential gradient; minerals are absorbed by active transport.

What is the purpose of active loading in the phloem?

To transport sucrose by using ATP to create a diffusion gradient.

What happens to the water potential in the sieve tube when sucrose enters?

It is reduced, causing water to enter via osmosis.

What drives the mass flow of water in the phloem?

The hydrostatic pressure gradient.